Through the years a number of game balls have been developed and used in sports and amusement activities. While certain game balls are formed of a solid rubber sphere or the like, a great number of sport or game balls are formed of an elastic or resilient outer spherical shell within which a closed interior cavity confines a volume of pressurized gas such as air or the like. In accordance with the need in most sports activities to provide a substantial rebound or bounce characteristic, the pressure of the captivated gas within the game ball interior generally exceeds atmospheric pressure by a substantial amount.
The size and shape of such game or sport balls varies substantially. For example, in the sports of basketball, soccer and the like, the game ball comprises a relatively large sphere which is subject to very rigid standards of weight, size, pressurization and bounce characteristics. In further variance, the sport of American football uses an oblong ball having pointed ends while sports such as tennis and racquetball employ relatively small spherical game balls having extremely high bounce characteristics. Regardless of the substantial variety of sizes and shapes of game balls, all pressurized playing balls are subject to a common problem which is generally described as leakage. The leakage problem is simply the characteristic by which small amounts of the pressurizing gas within the ball escape leaving the ball with a reduced undesirable and sometimes unacceptable bounce characteristic.
In general, the larger game or sport balls, such as those used in basketball, soccer or American football, have for many years utilized a pressurizing valve within the ball structure and the inflation of the sport ball is a routine practice. In most instances, the larger mass of the large sport balls masks any unbalancing effect provided by the weight of the pressurizing valve. As a result, the leakage characteristic of such larger sport balls has not heretofore been found to be a serious problem.
In smaller game or sport balls such as bladderless tennis and racquetball, however, the leakage problem has been found to be more serious. In general, such smaller game or sport balls are manufactured without a pressurizing valve and are formed of a elastic shell under high pressure conditions which initially pressurizes the ball. During the course of the use of the game or sport ball and with the passage of time during extended periods of nonuse, the captivated pressurized gas within the ball interior usually diffuses through the minute pores of the shell material. While substantial efforts are exercised to maintain a low porosity of the ball skin, virtually all elastic shell materials found to date are sufficiently porous to permit slow leakage. In addition, the game activities to which the smaller sport or game balls such as tennis and racquetball are subjected, provide for repeated and frequent hard impacts against the players' racquets and the surrounding playing court surfaces. The combined effect of these conditions is to cause leakage of the game ball and a change in the bounce characteristic of the ball. Since even small changes of bounce characteristic provide unacceptable performance for the game ball in sports such as tennis and racquetball, such balls must be either repressurized or discarded.
The need to repressurize the smaller game or sport balls or to maintain the pressurization of such balls between use has led practitioners in the art to devise various pressurized containers to be used in storing the smaller sport or game balls. While the structures of such devices vary substantially, all provide the common operative element of an interior cavity together with means for supporting one or more such smaller sport or game balls in a pressurized environment. The operative mechanism of such pressurized storage containers is simply to subject the ball to a pressurized environment substantially greater than the pressure within a game ball having suffered some loss. The same porosity which in normal use and storage provides for a slow diffusion of the pressurized interior gas through the outer shell, also permits a similar slow diffusion inwardly through the outer shell from the pressurized storage environment to the ball interior. After an extended period of time, the game or sport balls are returned to the desired pressure and may be used. While this process prolongs the life of game or sport balls and permits repeated pressurization of the game or sport balls, it requires a considerable storage time to achieve the desired effect.
Because of the desire to circumvent the substantial storage time required to repressurize a game ball in such pressure storage containers, practitioners in the art have made several attempts to provide a valve mechanism for use in the smaller game balls. One such attempt is found in U.S. Pat. No. 2,830,610 issued to Chupa for a VALVE FOR PLAY BALLS in which a playing ball defines a resilient outer shell having an aperture therethrough which provides access to the ball interior. A valve mechanism defines a generally conical projection extending through the aperture and into the ball interior. The valve structure further includes an extending flange on its outer surface which is attached to the exterior surface of the ball shell around the aperture in a sealing attachment. The valve defines an interior passage which receives the needle portion of a conventional ball inflating device.
U.S. Pat. No. 4,012,041 issued to Hoffman sets forth a GAME BALL REPRESSURIZING METHOD in which a game ball is provided with an inwardly extending generally cone-shaped valve member which may be separately manufactured and inserted into an aperture in the game ball shell or which may be integrally molded into the game ball outer shell. The valve member includes a pair of thin flanges or lips arranged side by side which allow air to pass freely into the ball when the pressure outside the valve is greater than the pressure inside the valve but which sealingly close when the pressure inside the ball exceeds the external pressure. A cooperating inflating device configured to operate the valve is shown which may be utilized to repressurize the game ball.
While the provision of a game or sport ball of the smaller variety having a pressurizing valve is generally desirable, the valves provided to date have been subject to several problems. One problem arises out of the extra weight provided by the valve mechanism itself. Because the valve weight is substantial in comparison to the surrounding shell material of the ball, the concentration of mass imposed on the ball by the pressurizing valve tends to unbalance the ball. In addition, such valve structures have been found themselves to be susceptible to leakage over time and is effected by the striking of the ball near the valve region. Finally, the use of such valve mechanisms can be costly and increase the expense of ball manufacture.
As a result, there arises a need in the art for a pressurizable game ball and pressurizing valve which is maintained in closure by a mechanical advantage and which provides a low cost reliable valve mechanism and which does not simultaneously unbalance the ball.